Conservation of Mass

Learning Resource Type

Classroom Resource

Subject Area

Science

Grade(s)

5

Overview

In this lesson, students will be able to make measurements showing that whether the process is a change of state, dissolving, or a chemical reaction, the total mass of the substances does not change. Students check to see whether the mass of ice and water in a cup changes as the ice melts. Students also test whether the combined mass of sugar and water changes after sugar is dissolved in the water. As a demonstration, students will observe that a precipitate forms in a reaction between solutions of magnesium sulfate and sodium carbonate, and that the mass of the products is the same as the mass of the reactants.

Science (2015) Grade(s): 5

SC15.5.2

Investigate matter to provide mathematical evidence, including graphs, to show that regardless of the type of reaction (e.g., new substance forming due to dissolving or mixing) or change (e.g., phase change) that occurs when heating, cooling, or mixing substances, the total weight of the matter is conserved.

UP:SC15.5.2

Vocabulary

  • Quantitative measurements (mass, weight, standard unit)
  • Physical quantities (weight, time, temperature, volume)
  • Property changes
  • Matter
  • Reaction
  • Heating
  • Cooling
  • Mixing
  • Physical properties
  • Conservation of matter
  • Graphing

Knowledge

Students know:
  • The amount (weight) of matter is conserved when it changes form, even in transitions in which it seems to vanish.
  • No matter what reaction or change in properties occurs, the total weight of the substances does not change. (Boundary: Mass and weight are not distinguished at this grade level.)

Skills

Students are able to:
  • Measure and graph the given quantities using standard units, including: the weight of substances before they are heated, cooled, or mixed and the weight of substances, including any new substances produced by a reaction, after they are heated, cooled, or mixed.
  • Measure and/or calculate the difference between the total weight of the substances (using standard units) before and after they are heated, cooled, and/or mixed.
  • Describe the changes in properties they observe during and/or after heating, cooling, or mixing substances.
  • Use their measurements and calculations to describe that the total weights of the substances did not change, regardless of the reaction or changes in properties that were observed.
  • Use measurements and descriptions of weight, as well as the assumption of consistent patterns in natural systems, to describe evidence to address scientific questions about the conservation of the amount of matter, including the idea that the total weight of matter is conserved after heating, cooling, or mixing substances.

Understanding

Students understand that:
  • Standard units are used to measure and describe physical quantities such as weight and can be used to demonstrate the conservation of the total weight of matter.

Scientific and Engineering Practices

Using Mathematics and Computational Thinking

Crosscutting Concepts

Scale, Proportion, and Quantity

CR Resource Type

Lesson/Unit Plan

Resource Provider

American Chemical Society

License Type

Custom

Accessibility

Video resources: includes closed captioning or subtitles
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